1. Field of the Invention
The present invention relates to an ultrasonic transmission member.
2. Description of the Related Art
Ultrasonic transmission members are widely used in, for example, an endoscope, an ultrasonic welding machine, or the like.
U.S. Pat. No. 6,325,811 B1 discloses an elongated ultrasonic transmission member (ultrasonic waveguide) which is inserted from a proximal end portion of an insertion part of an endoscope up to a distal end portion thereof for use, and a distal end portion of the ultrasonic transmission member is attached with a clamping arm member such that the clamping arm member is openable and closable.
U.S. Pat. No. 5,484,398 discloses an elongated hollow ultrasonic transmission member (tubular tool) which is inserted from a proximal end portion of an insertion part of an endoscope up to a distal end portion thereof for use.
Further, U.S. Pat. No. 5,997,497 discloses an elongated ultrasonic transmission member which is inserted from a proximal end portion up to a distal end portion for use in an endoscope.
Since each of these conventional ultrasonic transmission members must have a high dimensional precision in order to transmit an ultrasonic wave from its one end to its another end efficiently and since they need corrosion resistance, they are formed by machining a metal material, such as titanium, titanium alloy, aluminum alloy, or nickel-aluminum alloy.
Machining of these metal materials with high dimensional precision needs much time required for forming the conventional ultrasonic transmission member and increases its forming cost.
Metallic glass attracts attention as a material which does not include a crystal grain boundary and which is therefore excellent in corrosion resistance, strength, elastic modulus, formability, and shape transfer property, as compared with the metal materials. For example, Japanese Patent Application KOKAI publication No. 10-202372 discloses that two or more members are integrally joined to each other by using metallic glass. Japanese Patent Application KOKAI publication No. 2000-343205 discloses that metallic glass is formed in a cylindrical shape in a supercooled liquid region thereof. Further, Japanese Patent Application KOKAI publication No. 09-323174 discloses that two or more members are integrally joined to each other by using metallic glass.
The metallic glass is a kind of amorphous alloy obtained by melting a plurality of (at least three) crystalline metals by utilizing arc-discharge or the like to produce an alloy and then cooling the alloy rapidly, and has a supercooled liquid region (glass transition temperature zone) of a predetermined temperature range. The metallic glass exhibits an excellent shape transfer property in the supercooled liquid region (glass transition temperature zone), similarly to forming glass while it is softened by heating. When rapid cooling is performed after the plurality of crystalline metals are melted to be alloyed as described above, the melted alloy is poured into a casting cavity of a mold so that the shape and dimensions of the casting cavity of the mold can be transferred precisely, as in a case where melted glass is poured into a casting cavity of a mold. For example, a charging rate of metallic glass of an Ni group is as high as about 99%, as compared with that the charging rate of an ordinary aluminum alloy for die-casting to a predetermined casting cavity of a predetermined mold is about 84%.
The plurality (at least three kinds) of crystalline metals are different from each other in their element dimensions, and, after they are alloyed as described above, they are not arranged regularly so that they are not crystallized. The plurality (at least three kinds) of crystalline metals after they are alloyed have an energy amount less than that before they are alloyed, so that they are mixed more easily. Various amorphous alloys having a property which can be called as a “metallic glass” have been known, and for example Zr55Cu30Al10Ni5 comprising four kinds of metals of Zr, Cu, Al, and Ni is relatively widely known.
This amorphous alloy can be obtained by melting four kinds of metals of Zr, Cu, Al, and Ni at a temperature of about 1200° C. and then cooling the melted metals rapidly at a cooling rate of 10 K/sec or more, and, in this amorphous alloy, a temperature range between about 400° C. and about 450° C. is a supercooled liquid region (glass transition temperature zone).
In addition to the excellent shape transfer property and formability as described above, metallic glass has a low Young's modulus equivalent to that of a conventional crystalline alloy such as magnesium alloy, duralumin, titanium alloy, stainless steel, or ultrahigh tensile strength steel and is considerably superior in tensile strength to the conventional crystalline alloy. Further, metallic glass has a corrosion resistance of at least 10000 times that of conventional stainless steel.